A DNAzyme that targets the CAG repeat RNA in polyglutamine diseases

Description of Invention

The invention is a synthetic single-stranded DNA molecule that functions as a specific RNA-cleaving DNA enzyme (or DNAzyme) as a potential therapeutic for the treatment of polyglutamine diseases. The binding arms of this synthetic DNAzyme are complementary to the CAG repeats found in the pathological expansion of CAG trinucleotide repeats in the translated region of unrelated genes. Proof of concept was demonstrated when pathological polyQ protein clones were transfected into HEK293T cells. Complete knockdown of expression of these proteins was observed when the cells were subsequently transfected with the DNAzyme. The DNAzyme appears to fully functional at physiological concentrations of Mg2+. Suppressing expression of the toxic gene product represents a promising approach to therapy for polyglutamine diseases.

 

Stage of Development

In vitro data: Proof of concept has been demonstrated in cell culture systems. Pathological polyQ protein clones were transfected into HEK293T cells. Complete knockdown of expression of these proteins was observed when the cells were subsequently transfected with the DNAzyme.

In vivo data: A rodent study is underway to demonstrate safety of the DNAzyme.  At the midpoint of the study, no adverse effects have been observed.

 

Competitive Landscape

Currently there is only one DNAzyme therapeutic in clinical development.  Development of DNAzymes have been hampered in the past due to inactivity of the DNAzymes at physiological cation concentrations.  The inventors have developed a DNAzyme that is fully functional at physiological concentrations of Mg2+ and Ca2+.

 

Competitive Advantages

•      DNAzymes are a safer approach than DNA-manipulating strategies such as the CRISPR-Cas system.

•      DNAzymes are more stable than RNA-based therapies.

•      DNAzymes as single-stranded DNAs are cost effective and easy to synthesize.

•      DNAzyme can be chemically modified to improve biostability and compatibility the versatile delivery systems.

•      DNAzymes bypass the proteinaceous enzyme requirement as opposed to some therapeutic approaches such as antisense oligonucleotides.

 

 

Patent Information:
Licensing Contact
Joe Jilka
jjilka@houstonmethodist.org

Inventors:
Nan Zhang
Tetsuo Ashizawa